XX XX SCOPE CYCLING WHITEPAPER 1
CONTENTS EDITORIAL Contents 3 Four Wheels, One Philosophy 4 Brand Introduction 5 Performance Matters Development Process 6 Eight Steps to Success Optimized Aerodynamics 8 Optimum Balance 10 The Panel Method 12 Computational Fluid Dynamics (CFD) 13 CFD Validation, Prototyping and Wind Tunnel Testing Light Weight 14 Finite Element Analysis 15 Local Reinforcement Brake Performance 17 Heat Resistance Improved Durability 19 Customized Bearings Authors Nikhilesh Tumuluru, BSc Mathijs Eversdijk, I.R. Dr. Veit Hammer Editors Nieck Busser Rik Kusters Mathijs Burger Lateral Stiffness 20 Wide Flange Distance Development and Validation 22 The Final Step Photography Jeroen van der Wielen Sean Louw Monkey Town CT Joe Flannery
FOUR WHEELSETS ONE PHILOSOPHY At Scope Cycling our goal is to provide our customers with the best possible riding experience. We puzzle, we try, we fail, and do it all over again until we succeed: without any compromise. By combining innovation and passion, we are able to manufacture the best performing carbon wheels available. Our R series wheelsets are the result of extensive research, analysis, and thoughtful design. We developed each wheelset with a given purpose in mind. And for your road ahead. The same goes for our O2 wheelset, which is dedicated for off-road usage. We launched the R series wheelsets in 2015. Since then, they have exceeded the expectations of both our sponsored athletes and customers. In 2017 we added the O2 wheelset, which was almost instantaneously perceived as a benchmark in its category. This white paper discusses the importance and balance of aerodynamics, lateral stiffness, light weight, braking performance, durability, and compliance that make Scope wheelsets bestin-class. 3
BRAND INTRODUCTION Scope Cycling is a brand made in cycling. The company was founded by former professional riders Rik Kusters and Nieck Busser, who look back at more than 350 races and 200.000 km. combined. Their experience is the basis for all our products. All Scope products are developed inhouse at our facilities in Eindhoven, The Netherlands. The area is known as one of Europe s most thriving centers for technological innovation, and design. It is the perfect environment for us to manufacture products that are setting new standards. We develop our products in close collaboration with the University of Technology Eindhoven, the University of Technology Delft, and well-established brands Schwalbe, SKF, and CeramicSpeed. Starting from scratch we have developed our own hubs and rims, focusing on the optimization of key aspects such as shape, width, weight and stiffness. Our findings are verified in the wind tunnel, and our wheelsets have been put through their paces by our sponsored athletes. With one result: the best performing wheelsets available. No Excuse! 4
PERFORMANCE MATTERS Cycling is about passion. It is about the hard work for those precious memorable moments. There are different factors that are of importance in order to achieve goals. One of these factors is the performance of the material one uses. However, since technological gains are marginal in modern-day cycling, it is important to focus on the details that make a good product an outstanding one. Based on our background in the sport, we have set ourselves a few unique design principles. One of the main principles is to approach each wheel as a system. Instead of just combining individual designed components, we have developed the rims and hubs of all Scope wheelsets ourselves. And we keep on improving them by closely looking at, and, where it makes sense, implementing the latest relevant technologies in order to make our products even better. Our focus on developing and optimizing each wheel as a system allows us to stay ahead of the competition. And it allows us to provide you with wheelsets that form the perfect balance between aerodynamics, stiffness, weight, durability, and compliance. 5
DEVELOPMENT PROCESS Eight Steps to Success At Scope Cycling, we want to develop the best performing wheels for both your road and off-road adventures, no matter if you are a racer at heart or just simply enjoy the time in your saddle. To achieve that goal we have defined a set of eight development steps. of our study, we create a sketch design. This is then transferred into a 3D-drawing. During that phase of the process, we make extensive use of Computational Fluid Dynamics (CFD) and Finite Element Analysis (FEA). This helps us to define the shapes of our rims, hubs and wheels. Printed 3D-models then help to validate these shapes in the wind tunnel. Our development process starts with a benchmark study. Besides looking at and comparing recently developed products from competitors, we also take the latest findings of scientific research into account. Based on the outcome Once we have decided on a specific shape, tooling production and sample production build the next step. The final steps of our development process are pre-production and mass-production. During this phase, field tests are becom- 6
DEVELOPMENT PROCESS ing relevant to confirm the performance of our designs in any condition. If deemed necessary, we start with another development circle, after all eight steps have been completed. To stay best-in-class with our products. 1. BENCHMARK STUDY 2. SCETCH DESIGN 3. 3D-DRAWING 4. 3D-PRINT CONTINIOUS IMPROVEMENT 5. TOOLING PRODUCTION 6. SAMPLE PRODUCTION 7. PRE- PRODUCTION 8. MASS PRODUCTION 7
OPTIMIZED AERODYNAMICS Optimum Balance There are different factors that determine the aerodynamic performance of a wheel. The main factors are, however, the rim depth and the rim shape. While it is widely known that deeper rims provide better airflow, it is their specific shape that defines the aerodynamic stability and as such, how a wheel feels when being ridden. Deeper rims are more prone to crosswinds than their shallower counterparts. A wheel with deep rims is, therefore, harder to control in crosswind situations. In order to give a rider greater confidence to choose a deep rim wheel in challenging conditions, it is important to increase its overall stability or, in other words, to find the optimal balance between low drag and crosswind influence. For our R series wheels we ve done exactly that. Together with a select group of athletes, we collected real ride wind data for more than one year. This allowed us to find out under which circumstances a wheel felt stable or unstable. We then made use of a detailed CFD analysis in partnership with the R5c CFD analysis 15 degree angle 8
OPTIMIZED AERODYNAMICS TU Eindhoven and the TU Delft to define the characteristic 26mm U-shape rim profile of our R3, R4, and R5 models. As part of the process, we designed the rim shape starting from the tire to allow the latter to perfectly fit and to also create a smooth airfoil between the two of them. We then verified our findings in the Flanders Bike Valley wind tunnel, before validating them with our sponsored athletes. As the result of an extensive development process, our R series wheelsets set a new benchmark for aerodynamically optimized carbon wheelsets. Developed in collaboration with: 9
OPTIMIZED AERODYNAMICS The Panel Method CFD helped us to determine pressure drag as the main cause of resistance. It also helped us to understand that the most favorable shape for an aerodynamically optimized rim would reduce drag without adversely affecting side force. To achieve that, we needed to develop a shape that combined the positive aspects of extreme V-shape profiles with the ones of toroidal shape profiles. There are different methods that can be helpful when developing a rim profile. One of the most popular methods at the moment seems to be the optimization of algorithms that are coupled to CFD. However, we found it insufficient to use this method and took the rather unusual choice to use the panel method to optimize the shape of our R series rims. The panel method is a surface-based flow analysis technique. We used it in conjunction with an optimization routine in MATLAB, which helped us to automatically generate shapes that satisfied the constraints with the objective function of reducing drag. Using the panel method allowed us to 10
OPTIMIZED AERODYNAMICS exert complete control on the rim shape. For the purpose of optimization, the rim was discretized into different elements. Each element was considered to be a polynomial of the 3rd degree. This is shown in the below figure with the curve being discretized into 50 elements. Since the curve had to be continuous and smooth, constraints were placed on the curve and its derivatives. The curvature radius towards the trailing edge was also constrained, to limit an excessive formation of a V-shape. As a result, we were able to define a rim shape that reduced drag without compromising side force behavior. 11
OPTIMIZED AERODYNAMICS Computational Fluid Dynamics (CFD) We used Computational Fluid Dynamics (CFD) to develop our current generation of R series wheelsets, since the method allows for a variety of test runs of different models within an efficient amount of time. Besides learning more about the airflow around our 3D modeled prototypes, this method also helped us to further improve and optimize the chosen rim shapes for the R3, R4, and R5 models. To understand the full scope of the aerodynamically relevant aspects, we looked at the performance of a complete wheel with tire, spokes, and hub, while considering variables such as wheel rotation, moving ground, wheel in ground effect, and frame interaction. In order to capture and resolve pressure drag, a computational domain of 2D, and 3D proved to be a sufficient choice. To investigate the drag force variations over a range of yaw angles ranging from 0-20 degrees, we ran steady state RANS simulations and tested different turbulence models to capture the correct flow dynamics. We used the best models for the optimization. Top views of wheel interaction at 10 degree yaw 12
OPTIMIZED AERODYNAMICS CFD Validation, Prototyping and Wind Tunnel Testing Once we defined the rim shapes for the R series wheelsets, we validated them using CFD. This allowed us to ensure that we had found the most favorable shapes for aerodynamically optimized rims and to build prototypes. We printed 3D models of the R3, R4, and R5 rims and also build respective carbon prototypes. All prototypes were then tested in the Flanders Bike Valley wind tunnel to confirm our CFD findings. The wind tunnel test helped us to further understand the interaction of the optimized wheel with aspects such as rotation, fork and frame, as well as rider. It was also crucial to determine the final shape of our R-series rims. Although our chosen optimization and validation method is somewhat similar to inverse airfoil design, it had, to date, not been applied to bicycle rims. And while our approach might seem unique inside the cycling industry, it actually brings our core values to the fore: Trying to push boundaries without any excuse. 36 WEIGHTED AVERAGE 35 34 Drag/Watts 33 32 31 30 29 SCOPE R5c Competitor 1 Competitor 2 Competitor 3 Competitor 4 Competitor 6 Competitor 7 Competitor 8 13
LIGHT WEIGHT Finite Element Analysis There are different ways to find the perfect shape for an aerodynamically optimized rim. While CFD played an important role during the development process of our R series wheelsets in terms of understanding the airflow of these, we used the Finite Element Analysis (FEA) during the design phase to reduce the actual number of physical prototypes, thus allowing us to focus on the studies of these prototypes in more detail. Using this method allowed us to define the overall strength of our rims and hub flanges, including specific reinforcement points. Strength analysis using FEM 14
LIGHT WEIGHT Local Reinforcement Weight is a factor that shouldn t be underestimated, when it comes to the overall performance of a wheel. It influences acceleration, behavior at speed, and general handling characteristics. The rims of our road and off-road specific wheelsets are manufactured using different types of carbon. In our hubs we also use special aluminums such as AL7075. This allows us to reduce the weight of our wheels as much as possible, without sacrificing their durability and stiffness. We have developed our own Local Reinforcement Technology (LRT). This unique production technology locally reinforces the rim at the spoke holes, whereas normally the entire spoke hole section is reinforced. Using this technology allows us to save up to 40 grams per rim. To use a lightweight rim is important in order to achieve a more efficient utilization of a wheel s rotational energy. In contrast, a light yet durable hub helps to increase the lifetime of a wheel. 15
LIGHT WEIGHT 2000 WEIGHT COMPARISON REAR WHEEL 1800 1600 1400 1200 Grams 1000 800 600 400 200 0 Zipp 202 NSW SCOPE R3c Zipp Firecrest 202 Zipp 303 NSW SCOPE R4c Zipp Firecrest 303 Mavic Exalith SCOPE R5c Vision Metron 5 Zipp Firecrest 404 Zipp 404 NSW Zipp 454 DT Spline 1400 Zipp 808 NSW 16
BRAKE PERFORMANCE Heat Resistance For rim brake wheels the temperatures reached can become as high as 280 degrees Celsius during prolonged heavy braking. Therefore, developing a brake surface that can handle temperatures up to that point without causing failure to the rim is crucial. Our R series rim brake models can handle the mentioned temperature point. In order to achieve this high level we developed our own resin. By using it in combination with a special production process we can ensure a consistent layup for the braking surface. We think that the ideal braking behavior should be linear and easy to control. We achieve that by using our own brake pads. We have developed the compound for these in-house. We also make use of a special additive in the braking surface of the rim. For disc brake wheels, the forces on the spokes and rim are more important as the heat is generated in a steel disc rotor and thus kept away from the composite rim. To test the braking behavior of our wheels we use a test setup which spins up a wheel using an electric motor driving the wheel on the tire. 17
BRAKE PERFORMANCE Heat resistance test 18
IMPROVED DURABILITY Customized Bearings As just mentioned, durability is mainly a factor to bear in mind when developing a hub. Depending on the hub design, one can influence how prone the used bearings are to wear and tear. This, in total, helps us to optimize the durability of the hubs. Developed in collaboration with: To be able to keep the bearings safe from dirt and water, we developed our own system. We cover the bearing sides next to the axle end-caps and use our own seals and grease inside the bearings. We do further use SKF industrial bearings as a standard and offer CeramicSpeed bearings as an upgrade. 19
LATERAL STIFFNESS Wide Flange Distance All Scope Cycling wheels are built as a system. To create a very high lateral stiffness while keeping an equal spoke tension, we optimized the flange distance of our hubs. A wide flange distance is essential, since nearly 60 percent of the lateral stiffness are determined by the flange distance. Other important aspects are the amount of spokes, their thickness, and the stiffness of the rim. While the combination of amount and thickness of the spokes determines around 25 percent of a wheel s overall lateral stiffness, the stiffness of the rim contributes another 15 percent. The uniform lateral stiffness of our wheels is between 47-52 Nm/mm. We use our own test device for the measurements and carry them out by applying 25 kilogram load on a wheel by pulling its rim outwards. Thereby, the measurement process is the same for both front and rear wheel. 20
LATERAL STIFFNESS 60 LATERAL STIFFNESS REAR WHEEL 50 40 Nm/mm 30 20 10 0 SCOPE R5c SCOPE R4c SCOPE R3c DT Spline 1400 Zipp Firecrest 404 Mavic Exalith Zipp Firecrest 303 Zipp 808 NSW Vision Metron 5 Zipp Firecrest 202 Zipp 454 Zipp 404 NSW Zipp 303 NSW Zipp 202 NSW 21
DEVELOPMENT PROCESS AND METHODS The Final Step The final step of our development process is the same for both our road and off-road products. While for the latter aerodynamic aspects play a minor role, other aspects are of more importance. Once we decide on the shape of the rim, the design of the hub, and the spoke pattern to realize the optimal performance of all our wheels, we determine the composite manufacturing process, the laminate, the building process, and quality control measures. In addition to test our wheels for all industry required standards, we also control them with our own parameters. These include brake performance, impact, maximum pressure, rolling fatigue, and spoke strength tension. Only if a minimum of 50 wheels per model of our pre-production order has passed our rigorous testing protocol we approve the final production. Our sponsored athletes do then help us to test our wheels in the field to further validate our chosen designs and to verify their durability. Training and racing on them around the globe under the most extreme conditions is the final proof for both our R series and Off-road wheelsets. 22
XX XX COMFORTABLE CLIMBER BRAKE OPTION: RIM / DISC BRAKE COLOR OPTION: BLACK / WHITE RIM DEPTH EXTERNAL RIM WIDTH INTERNAL RIM WIDTH SET WEIGHT HUBS / BEARINGS SPOKES RIM BRAKE SPOKES DISC BRAKE COMPATIBILITY 30 mm 26 mm 19 mm Tubeless Rim: 1440 gr Disc: 1477 gr Scope SKF bearings Sapim CX - Ray Sapim CX - Sprint Shimano / Campagnolo / XD 23
XX XX OUTSTANDING ALLROUNDER BRAKE OPTION: RIM / DISC BRAKE COLOR OPTION: BLACK / WHITE RIM DEPTH EXTERNAL RIM WIDTH INTERNAL RIM WIDTH SET WEIGHT HUBS / BEARINGS SPOKES RIM BRAKE SPOKES DISC BRAKE COMPATIBILITY 45 mm 26 mm 19 mm Tubeless Rim: 1550 gr Disc: 1557 gr Scope SKF bearings Sapim CX - Ray Sapim CX - Sprint Shimano / Campagnolo / XD 24
XX XX AERO SPECIALIST BRAKE OPTION: RIM / DISC BRAKE COLOR OPTION: BLACK / WHITE RIM DEPTH EXTERNAL RIM WIDTH INTERNAL RIM WIDTH SET WEIGHT HUBS / BEARINGS SPOKES RIM BRAKE SPOKES DISC BRAKE COMPATIBILITY 55 mm 26 mm 19 mm Tubeless Rim: 1595 gr Disc: 1632 gr Scope SKF bearings Sapim CX - Ray Sapim CX - Sprint Shimano / Campagnolo / XD 25
XX XX OFF - ROAD EXPERT COLOR OPTION: BLACK / WHITE RIM DEPTH EXTERNAL RIM WIDTH INTERNAL RIM WIDTH SET WEIGHT HUBS / BEARINGS SPOKES COMPATIBILITY 23 mm Off-set 3 mm 31 mm 25 mm Tubeless 1360 gr Scope SKF bearings Sapim Laser Shimano / XD 26
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